Abstract: According to the deficiency of traditional evaluation methods, a quantitative evaluation method is proposed to evaluate the carbon nanotubes' (CNTs) length distribution and the uniformity of the distribution. A simplified matrix can be obtained after the processing of carbon nanotubes solution TEM image. Making the first element of the simplified matrix as the original point, extracting different steplengths and all elements' sum of every step-length, disposing the date with linear curve fitting in the bilogarithm, the slope of the linear is CNTs' length distribution parameter p₁. Circles are drawn with different radius and with the TEM images' centroid as the circle center. CNTs' quantity were extracted from the circles and made coordinates of linear fitting in bi-logarithm. Reciprocal value of the linear slope is just the dispersion uniformity parameter p₂. Appling the method to different carbon nanotubes dispersion uniformity, the results show that it can correctly evaluate the CNT length distribution and the uniformity of distribution.